The present invention relates generally to an orientation sensor especially suitable for use in an underground boring device, and more particularly to a number of specifically configured orientation sensors and the way in which they are used to monitor pitch and/or roll of an object such as a remotely controlled underground boring device.
Presently, there are a number of different known types of orientation sensors which have been designed especially for use in remote controlled underground boring devices. One example can be found in U.S. Pat. No. 4,674,579 (Geller). Another example can be found in U.S. Pat. No. 4,714,118 (Baker). Still another example is described in Applicant""s own U.S. Pat. Nos. 5,155,442, 5,337,002, and 5,444,382. These patents are incorporated herein by reference. As will be seen hereinafter, the present invention is directed to a number of specifically improved features not disclosed or made obvious in view of the exemplified prior art.
As will be described in more detail hereinafter, the orientation sensor disclosed herein includes a sensor housing defining a housing chamber, an arrangement of electrically conductive members in a predetermined positional relationship to one another within the chamber, and a flowable material contained within the chamber and through which electrical connections between the electrically conductive members are made such that a comparison between an electrical property, for example voltage, of a first combination of conductive members to the corresponding electrical property of a second combination of conductive members is indicative of a particular orientation parameter, specifically pitch or roll, of the orientation sensor.
In one embodiment of the present invention, the arrangement of electrically conductive members includes first and second such members disposed at first and second spaced apart locations, respectively, within the chamber and at least one electrically conductive wire supported by the housing and including a segment thereof disposed within the chamber at a location between the first and second electrical members. In this embodiment, the flowable material contained within the housing chamber makes an electrical connection between the first and second conductive members and the wire segment such that the comparison referred to above is a ratio and this ratio is indicative of the displacement of the flowable material within the housing chamber, whereby the orientation sensor is capable of generating an output voltage indicative of the pitch position of the sensor. Preferably, this embodiment of the present invention utilizes at least two wires which are electrically connected together and which include segments thereof crossing one another within the housing chamber, preferably within a common plane centrally located between the first and second members and perpendicular to one another.
In a second embodiment of the present invention, the orientation sensor disclosed herein includes an arrangement of electrically conductive members including an array of at least four electrically unconnected wire segments extending into the housing chamber in a predetermined positional relationship to one another within the housing and a flowable material contained within the housing chamber and through which electrical connections between the electrically conductive members are made such that, for any given roll position of the sensor, a predetermined combination of the conductive members including certain ones of the wire segments will be placed in contact simultaneously with the flowable material so as to generate an output voltage corresponding to the combination and thereby represent the roll angle of the sensor. In a preferred configuration of this embodiment, the housing chamber is configured so as to define a central elongation axis and the array of four wire segments is located within the chamber in a substantially common plane perpendicular to the elongation axis such that, if the housing is oriented so that one of the wire segments is at a twelve o""clock position, the other three wire segments are positioned at three, six and nine o""clock respectively, with respect to the position of the first mentioned wire segment.
In still another embodiment of the present invention, the arrangement of electrically conductive members include first, second, third, fourth, and fifth such members disposed at first, second, third, fourth, and fifth spaced apart locations, respectively, within an elongated housing chamber and along the chamber""s elongation axis such that the first and third members are disposed at substantially the ends of the chamber, the second member is disposed at substantially the center of the chamber, and the fourth and fifth are disposed on opposite sides of the second member between the latter and the first and third members, respectively. A flowable material is contained within this chamber and through which electrical connections between the electrically conductive members are made (1) such that, in one mode of operation of the sensor, the ratio between an electrical property, for example voltage, of the first member and second member to the corresponding electrical property of the third and second member is indicative of displacement of the flowable material within the housing chamber, whereby the pitch sensor is capable of generating a first mode output voltage which is also indicative of the pitch position of the sensor, and (2) such that, in a second mode of operation of the sensor, a ratio between the same electrical property of the fourth member and second member to the corresponding electrical property of the fifth member and the second member is also indicative of displacement of the flowable material within the chamber, whereby the pitch sensor is capable of generating a second mode output voltage which is also indicative of the pitch position of the sensor. In this latter embodiment, the various electrically conductive members could be configured as rings, cylinders, and/or plate members (in the case of the first and third members) and arrays of wire segments (in the case of the second, fourth, and fifth members).
In accordance with a further embodiment of the present invention, at least three electrically conductive members are contained within an elongated housing chamber which also contains a flowable material of the type described previously such that the sensor serves to measure pitch. In this embodiment, the three conductive members can be configured as rings, plates, cylinders and/or arrays of wire segments. However irrespective of the particular configuration of each conductive member, means are provided for adjusting to a limited extent the positional relationship between these members along the elongation axis of the housing chamber, whereby to calibrate the output voltage of the sensor with respect to displacement of flowable material within the chamber. In a preferred arrangement of this embodiment, the first and third conductive members are located at or near the end of the chamber and the second member is located approximately the center of the chamber, longitudinally speaking, and the adjusting means includes means for moving one of the first and third members along elongation axis to a limited extent, towards and away from the second member.